MINIFICPP-1577: Separate build and test steps in ubuntu-20.04 ci job
MINIFICPP-1577: Separate build and test steps in ubuntu-20.04 ci job

Signed-off-by: Arpad Boda <aboda@apache.org>

This closes #1095

dtrodrigues/nifi-minifi-cpp,dtrodrigues/nifi-minifi-cpp,dtrodrigues/nifi-minifi-cpp,dtrodrigues/nifi-minifi-cpp,dtrodrigues/nifi-minifi-cpp